Method of producing a staple fiber yarn



May 25, 1954 H. E. NEW

METHOD OF PRODUCING A STAPLE FIBER YARN Filed May 24, 1950 A ass #10?/en 77/; 0/ 6fap/e//'/b 2/5 IN V EN TOR. HARRY E. NEW BY ATTORNEPatented May 25, 1954 UITED STATES PATENT OFFICE METHOD OF PRODUCING ASTAPLE FIBER YARN Harry E. New,

American .Viscose Corporation,

Swarthmore, Pa., assigncr to Wilmington,

6 Claims.

This invention relates to the production of artificial yarns and fabricshaving increased resilience. More particularly the invention relates toa method of drafting an artificial filament strand, such as a sliver orroving, in such manner that yarns and fabrics produced therefrom haveincreased resilience and luster.

In the manufacture of yarn from staple fiber, it is the practice to formthe fibers into a strand, sliver, or roving which in turn is drawn andtwisted into a yarn. It .is a common practice to subject textile fibersto a series of drafting or drawing operations which are designedespecially to bring the fibers into a more nearly parallel relationshipsothat when the final strand of loosely assembled fibers is twisted, themaximum strength of the fibers may be utilized.

A typical drawing mechanism used in a spinning frame comprises severalpairs of drawing rolls, usually three or four, each pair including alower and a cooperating upper roll, and the pairs being arranged, one inadvance of the other, so that they act successively on a continuousstrand or sliver guided through them. In a common arrangement, each pairis revolved at a higher speed than the pair immediately preceding it sothat during the travel of the sliver the fibers of which it is composedare drawn out, the sliver is attentuated, and the fibers are broughtinto a more nearly parallel relationship.

It has now been found that increase in the parallel relationship orstraight nature of the fiber when twisting into yarn results in a yarnwhich is not only stronger but also has increased resilience and lusterand fabrics made therefrom have increased crispness which is oftendesirable.

Rayon staple, including viscose, or acetate, and other synthetic fibers,are normally made with sufficient crimp in the fiber to facilitate fibercohesion during the carding and subsequent mill spinning operations,such as on the cotton system for example. The crimp may be formed byimmersing the fibers in hot water or by any other method suitable forthe particular fiber to be crimped. Short length fibers, for example 1to 3 inch staple length, normally processed on the cotton system,require considerable crimp and fiber cohesion in order to assist thefibers in holding together during processing. Other systems of spinning,such as the worsted, silk and linen systems, which use fibers from 3 toinches in length, do not require as much crimp in the fiber in order tofacilitate processing. Further, it is well-known that long fibers, whichare processed on the worsted, linen and silk systems,

give a yarn which is considerably firmer than the yarn produced on thecotton system using shorter length staples. This firmness is attributedto low drafting and longer, straighter fiber in the yarn.

It has long been the desire to successfully produce a yarn having thissame firmness from short or regular rayon staple fiber on the cottonsystem. Double carding, that is passing the crimped regular staple rayonfiber through the carding machine twice, has been proposed in order toproduce a rayon staple yarn having increased resilience. However, thisprocedure is undesirable due to increased cost and excessive staplebreakage, resulting in increased neppiness of the yarn.

It is a general object of the present invention to provide a methodwhereby short staple fibers, of viscose, or acetate rayon, and othersynthetic fibers, may be formed into a yarn on the cotton system havinga firmness comparable to those produced on the worsted, linen and silksystems.

It is another object of the present invention to produce a yarn formedfrom artificial staple fibers which has increased resilience and luster.

It is another object of the invention to provide a method of producing ayarn from artificial staple fibers wherein all the fibers are in morenearly parallel relationship.

It is another object of the present invention to produce a yarn whichwhen woven into a fabric imparts increased luster, resilience, andcrispness to the same.

Other objects and advantages of the present invention will be obviousfrom the description thereof hereinafter.

The objects of the present invention are generally accomplished bysetting the drafting rolls closer together in at least one stage ofdrafting than the minimum staple fiber length being processed and underlow draft conditions in order to straighten or parallelize the fiberswithout breaking them. While this may be accomplished at any draftingoperation, it is preferably done where the bulk of the stock is thegreatest, for

example, on the drawing frame.

The term drafting rolls refers herein to any pair of rolls in a draftingsystem which nip or clamp the fibrous material being attenuated tightlybetween them so as to substantially determine the linear speed of thematerial as it proceeds between them and practically prevent anysubstantial slipping of the material through them. It will be understoodthat the expression draft as used herein is broad enough to includeeither or both or any combination of a longitudinal slipping of thestaple fibers in the sliver as well as stretching or elongation of theindividual staple fibers. Where the ratch between the draw rolls is lessthan the shortest staple fiber length, elongation of the fibers isinherent.

While the present invention is equally applicable to any type'of staplefibenvsuch-ascotton, wool, viscose and acetate rayon, synthet'ic fibers,and the like, the same will be described in connection with viscosestaple fiber, but it should be understood that this is merely intendedto be i1- lustrative and not limitative.

In accordance with the present invention, it is usually necessary thatthe machine draft be maintained at a degree or i-peroent'ajge less thanthe extensibility of the staple fiber in order to avoid fiber breakage.However, under normal drafting conditions, a certain amount of fiberslippage occurs, in which case a slightly higher machine draft, i. e.,one higher than the extensiibilityof the staple fiber, may be maintainedthus taking :into consideration, or compensating for, the :fiberslippage. Thus, when using viscose staple fiber, which has anextensibility in the :range of from 15 to 20% when dry and trom 13 to2.2% when wet, in-accordance with the present invention, the actualdraft should not exceed 15 to 18% in the drafting zone where the rollsare set closer together than the staple length. The drafting ordrawingzone referred to herein may be defined as the 'efiective distancebetween the nipsofsucces'sive pairsof drafting-rolls, the-rolls "of eachpair being adjusted with sufficient .pressure to minimizeorsubst-antialiy eliminate fiber slippage. Such drafting rolls are to bedistinguished from control rolls which are not intended to preventslippage. It follows, therefore, that the term ratch, as used herein,refers to the lengthier drawing zone as defined above. It has beenZound, when processing viscose staple fiber, that maintaining a draft of153 or 1.3% be ween two sets of drafting rolls at the drawing frame witha "rollsetting closer than the staple length, that a materially firmeryarn'is produced.

As an illustration of the present invention, the followingspecificexarnple is set forth. Regular dull 3 inch viscose staple rayon(BB-denier) was processed through cotton machinery using a standardorganization for producing 16/1 yarn (since normal single-plyyarn runs"840 yards per pound, a 16/1 yarn is a sin leeply .yarn running 16 X 840yards per pound or 13,440 .yards per pound l. Special roll settings anddrafts were used-as follows and as illustrated in the accompanyingdrawing. A setting or ratch A (measured distance between the centers ofthe rolls) equal to 3% inches was employed be ween the pairs "of rollsamid, a setting B equal to 2' /2 inches between rolls 2 and 3, and asetting C ecjual to 3% inches between rolls 3 l. LA'dr'aft of 1114 to115 was employed between rolls 2 fand 3, there being an overall-draft of4.

A control sample was carried through using standard drawing rollsettings a n'd, organization. In the control setting A was equal t'o'3inches, setting B 3% inches, and setting '0 3 inches. An overall 01 lemployed. When the two yarns so produced were woven into 'fabrics andevaluated it was fountlthat the former yarn, or the one ting the closeroll settings a t-drawing produced a fabric having a firmer hand and ahigher luster than the latter or control.

in another aspect "of the present invention, a higher humidity 'bemaintained in the straightening zoneandjif desired, adrying zoneprocessing on the cotton system.

t may follow the strai htening zone and heat may be applied in thiszone. When employing a high humidity in the drafting zone, it ispossible to draft higher and straighten the fibers more due to the factthat the staple fiber normally has a higher extensibility when Wet.However, the

stretch requirements or amount of draft should not exceedith'eextensibility properties of the fiber at operating relative humidityconditions.

By means of the present invention, it is now possible to obtain firmyarn and fabric effects (similar to those presently obtained. only bythe use of long length fibers) from short length fiber Further, thepresent invention enables one to produce a yarn from short staple lengthfibers having greater yarn strength. Staple lengths as short as 1 /2inches maybe so'processed. While it is desirable that staple fiberpossess a slight criin it is possible to employ straight staple fibersin the present invention although the results are not as pronounced.

Among the many advantages of the present inventionmay be mentioned, inaddition to those hereinbefore pointed out, the ease with which themethod-is controlled. There is no additional cost over theregular cottonsystem of producing yarns. The present invention enables one to usestaple fibers to produce yarn having increased resilience. Also, itenables one to produce yarns on the cotton system having worsted or spunsilk system yarn characteristics.

As previously pointed-out, the roll setting will depend upon the lengthof the staple fiber being processed and the draft, on theextensibilityof such fiber. Further, it'should be note-1 that the invention isapplicable to any type of fiber draftingordrawing mechanism.

It should be understood that changes and variations may be made Withoutdeparting from the spirit and scope of the invention as defined in theap-pended"claims.

ll. A l'lfl9l3l510flf0l prod sing a staple fiber yarn comprising passing'a roving of 3-inch viscose rayonstap-le fibers through a drafting zoneunder a draft of about 1.14 to 1.15 and wherein the pairs of draftingrolls the ends of the zone are spaced 2%; inches apart, said staplefibers having 'an extensibility above 15%.

2. The method of producing staple fiber yarn which comprises "the stepsof passing a sliver of staple fibers through s. drafting zone having aratch less'than the minimum staple fiber length, and drafting the sliver.in said zone to impart an elongation to su'bstantiallyall of the fibersin the sliver.

3. An improved :draiting method for staple fiber sliver comprising stepsof compressing :asliver of staple fiber yarn between-roll nips having 'ar'at'ch not greater than the length of the individual staple fibers in"the sliver, and simultaneously elongating substantially all of thefibers injthes'liverbetween said nice.

4. An improved drafting method for staple fiber sliver comprising thesteps of compressing a sliver of staple fiber yarn between roll nipshaving a ratc'h not greater'than the length of the individual staplefiber yarn which comprises stretching a sliver of staple fibers in anamount less than the extensibility of the individual fibers in a drawingzone having a ratch not greater than the length of the shortestindividual staple fiber in the sliver to elongate the fibers in saidzone.

6. The method of producing a staple fiber yarn which comprises the stepof continuously elongating in a single drafting zone substantially allthe individual staple fibers in a sliver of staple fibers passingthrough said zone.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Name I Date Owen Dec. 25, 1928 Draper July 29, 1930 Reynolds Apr.15, 1941 Kettley June 3, 1941 FOREIGN PATENTS I Country Date GreatBritain Feb. 20, 1918

